What Would Happen If All of the Oceans on Earth Were Drained at the Deepest Point of the Mariana Trench

As part of their ongoing “What If?” series, Randall Munroe of xkcd and Henry Reich of MinutePhysics explained what would happen if a circular portal 20 meters in diameter appeared at the bottom of Challenger Deep in the Mariana Trench, known as the deepest known point on Earth, and began to drain all the water. The answer, at first, is not much.

It would take hundreds of  thousands of years for the ocean to drain. Even though the opening is wider than a basketball court and the water is forced through at incredible speeds, the oceans are huge. The water level would drop by much less than a centimeter per day. There wouldn’t even be a cool whirlpool at the surface ’cause the opening is too  small and the ocean is too deep.

If the portal grew exponentially in size, it would present a much more immediate problem that would grow greater and greater over time.

Great Britain,  Sri Lanka, New Guinea, Java, and Borneo  are now connected to their neighbors. And after 2000 years of trying to hold back  the sea, the Netherlands is finally high and dry (some of dikes they built would now hold  *in* the sea, rather than holding it out)As world experts on reclaiming land  from the ocean, now that they’re no  longer preparing for the constant  threat of a cataclysmic flood.